Aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene (BTEX) are carcinogenic and hazardous to human health even at relatively low concentrations. To ensure the safety of municipal water supplies, the Environmental Protection Agency (EPA) has mandated maximum allowable concentrations of 5 ppb, 1 ppm, 700 ppb and 10 ppm for BTEX, respectively. In recent years, industrial activities related to hydrocarbon production, processing, and transportation have resulted in BTEX contamination of water supplies. For instance, pipeline leaks have resulted in benzene contamination of groundwater in Parachute, Colo., and well water in Jackson, Wis. Additionally, hydraulic fracturing activity has been indicated as the cause of BTEX and gasoline-range organic contamination of the Pavilion, Wyo. aquifer.
Due to the increased health risks and remediation costs associated with larger contamination events, there is a strong motivation to develop portable, low-cost technologies, which can automatically sense BTEX contaminants and localize contamination events in real-time. Current state-of-the art sensing technologies such as gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detector (GC-FID) can selectively detect BTEX contaminants with exquisite sensitivity at ppt concentrations. However, due to cost, size, and energy requirements, these systems are not typically deployed in the field as real-time monitoring systems. Current monitoring methods typically involve sample collection in the field and transport back to a lab where the assay can be performed, resulting in delayed results and increased analysis costs.